1. Field of the Invention
The present invention relates generally to digital electronic circuits. More specifically, the present invention relates to wake-up reset circuits that generate integrated circuit (“chip”) reset upon a wake-up event.
2. Background of the Related Technology
Electronic circuits have been used to monitor the voltage of a power source to an electronic device in order to detect a required voltage threshold in generating a power on reset (“POR”) for the electronic device. The same or other circuits have been used to detect a brown out or power down condition. Typically POR and brown out detection circuits require a quiescent current at all times in order to function. For battery operated electronic devices, this quiescent current is a significant factor in the reduction of battery life, particularly for devices that are expected to be operable for extended periods of time. Other problems inherent with POR and/or brown out circuits are proper operation when a power source is below a critical voltage such that the digital logic circuits may be in unpredictable “meta-stable” states, and in applications in electrically noisy environments. Some success for these problems has been achieved using time delay and extensive filtering circuits.
There is, therefore, a need in the art for a reset circuit that does not require a continuous quiescent current, yet can reset a digital device, e.g., a digital processor, microcontroller, microprocessor, application specific integrated circuit (ASIC), programmable logic array (PLA), digital signal processor (DSP), etc., even when recovering from a low voltage or noisy condition.